Multiple Myeloma (also known as myeloma or plasma cell myeloma) is a progressive hematologic cancer of the plasma cell. The condition is characterized by excessive numbers of plasma cells in the bone marrow and overproduction of intact monoclonal immunoglobulin or free monoclonal light chains.
Clinically the disease is diagnosed, staged, and treated based on a variety of parameters which include the myeloma tumor cell mass on the basis of the amount of monoclonal (or myeloma) protein (M protein) in the serum and/or urine, along with hemoglobin and serum calcium concentrations, the number of lytic bone lesions based on a skeletal survey, and the presence or absence of renal failure. Additional approaches to characterizing the condition include the detection of greater than ten percent (10%) of plasma cells on a bone marrow examination, the presence of soft tissue plasmacytomas and the detection of free kappa and lambda serum immunoglobulin light chain. Bone marrow examination is done using standard histology and immunohistochemistry techniques. Additional cytogenetics of bone marrow samples may be conducted to determine prognosis. Follow up surveillance consists of chemistry and bone marrow evaluations if clinically indicated due to its invasive nature.
Currently, flow cytometric analysis of bone marrow is being evaluated as a tool for disease characterization and to distinguish between neoplastic plasma cell disorders from normal plasma cells and to detect minimal residual disease. Nonetheless, this approach continues to rely on an invasive procedure. There is significant need to develop less invasive techniques to detect, monitor and characterize the disease throughout its history and the presence of these cells in the blood may provide that opportunity.
In addition, more sensitive tools need to be developed for more accurate assessment of risk and monitoring for progression of disease in earlier stages of disease including monoclonal gammopathy of undetermined significance (MGUS) and Smoldering Multiple Myeloma. Some research data suggest that circulating plasma cells can be detected in earlier stages of disease and may correlate with prognosis, supporting the use of a standardized methodology to capture, enumerate and characterize these cells in earlier stages of disease.
The general consensus within the literature (Report of the European Myeloma Network on Multiparametric Flow Cytometry in Multiple Myeloma and Related Disorders. Andy C. Rawstron et al. Haematologica, 2008; 93 (3).) for the identification of abnormal plasma cells, particularly by flow cytometry, has included several key biomarkers consisting primarily of CD138, CD38 and CD45. Additional biomarkers such as CD19 and CD56 have also demonstrated utility in diagnosis.
The instant invention investigates circulating myeloma cells to evaluate whether these particular biomarkers either alone or in combination with one or more additional biomarkers or with FISH can be used for both the capture and detection of abnormal circulating plasma cells including detection of minimal residual disease. FISH can be used to detect numerous cytogenetic abnormalities that have been described in multiple myeloma. Translocations at the IGH locus, t(4;14), and deletions at the p53 locus, del(17p), have been shown to have prognostic value for event free and overall survival in multiple myeloma. (Genetic Abnormalities and Survival in Multiple Myeloma: The Experience of the InterGroupe Francophone du Myelome. Nerve Avet-Loiseau et al. Blood, 2007; 109: 3489-3495) These probes and several other multiple myeloma markers are available in the Poseidon catalog and could be adapted for use with the CellTracks® platform.
Commercially there exist immunomagnetic selection kits using CD138 magnetic particles. Stem Cell Technologies has an EasySep® Human CD138 Positive Selection Kit which can select CD138 positive cells from bone marrow and peripheral blood mononuclear cells (PBMC) and Miltenyi Biotech has CD138 Microbeads for the selection of CD138 positive cells from bone marrow, PBMC and whole blood. Analysis of collected samples is typically performed using flow cytometry.